Mastering Astronomy Chapter 15 - Galaxies - Tutorials Aid

The following figures give the approximate speeds at which five galaxies are moving away from Earth due to the expansion of the universe. Rank the galaxies based on the amount of redshift that would be observed in each galaxy's spectrum, from largest to smallest. -130,000 km/s -45,000 km/s -18,730 km/s -5,264 km/s -1,577 km/s

(Largest redshift) -130,000 km/s -45,000 km/s -18,730 km/s -5,264 km/s -1,577 km/s (Smallest redshift)

The following figures give the approximate speeds at which five galaxies are moving away from Earth due to the expansion of the universe. Rank the galaxies based on their distance from Earth, from farthest to closest. -130,000 km/s -45,000 km/s -18,730 km/s -5,264 km/s -1,577 km/s

(Farthest) -130,000 km/s -45,000 km/s -18,730 km/s -5,264 km/s -1,577 km/s (Closest)

Suppose that galaxy B is twice as far from Earth as galaxy A. Hubble's law predicts that galaxy B will be moving away from Earth with approximately _____. A) the same velocity as galaxy A B) four times the velocity of galaxy A C) half the velocity of galaxy A D) twice the velocity of galaxy A

D) twice the velocity of galaxy A

The following figures give the approximate distances of five galaxies from Earth. Rank the galaxies based on the speed with which each should be moving away from Earth due to the expansion of the universe, from fastest to slowest. -5 billion light-years -2 billion light-years -800 million light-years -230 million light-years -70 million light-years

(Fastest) -5 billion light-years -2 billion light-years -800 million light-years -230 million light-years -70 million light-years (Slowest)

Hubble's law is a relationship between galaxy speeds and galaxy distances. This relationship can be shown as a line on a graph of speed versus distance. Each of the following four graphs shows a possible relationship expressing Hubble's law. Rank the graphs based on their predictions of the speed, from fastest to slowest, for a galaxy located 400 million light-years away from Earth. -Speed away from Earth (km/s) 30000, Distance from Earth (millions of light-years) 400 -Speed away from Earth (km/s) 30000, Distance from Earth (millions of light-years) 600 -Speed away from Earth (km/s) 20000, Distance from Earth (millions of light-years) 1000 -Speed away from Earth (km/s) 15000, Distance from Earth (millions of light-years) 1200

(Fastest) -Speed away from Earth (km/s) 30000, Distance from Earth (millions of light-years) 400 -Speed away from Earth (km/s) 30000, Distance from Earth (millions of light-years) 600 -Speed away from Earth (km/s) 20000, Distance from Earth (millions of light-years) 1000 -Speed away from Earth (km/s) 15000, Distance from Earth (millions of light-years) 1200 (Slowest)

The following four graphs are the same as those from Part D, with each showing a possible relationship for Hubble's law. Rank the graphs based on the prediction they each would make for the current age of the universe, from oldest to youngest. -Speed away from Earth (km/s) 15000, Distance from Earth (millions of light-years) 1200 -Speed away from Earth (km/s) 20000, Distance from Earth (millions of light-years) 1000 -Speed away from Earth (km/s) 30000, Distance from Earth (millions of light-years) 600 -Speed away from Earth (km/s) 30000, Distance from Earth (millions of light-years) 400

(Oldest universe) -Speed away from Earth (km/s) 15000, Distance from Earth (millions of light-years) 1200 -Speed away from Earth (km/s) 20000, Distance from Earth (millions of light-years) 1000 -Speed away from Earth (km/s) 30000, Distance from Earth (millions of light-years) 600 -Speed away from Earth (km/s) 30000, Distance from Earth (millions of light-years) 400 (Youngest universe)

Active galactic nuclei can produce electromagnetic radiation from low-frequency radio wavelengths to high-frequency X-ray wavelengths. Some of this radiation comes from "thermal" sources involving material that has been heated to some characteristic temperature. Other radiation comes from "nonthermal" sources involving charged particles spiraling around magnetic field lines at speeds close to the speed of light. Here, the radiation that is emitted has nothing to do with the temperature of the source. Scientists have been able to reproduce this latter type of radiation in particle accelerators known as synchrotrons. For this reason, nonthermal radiation is often called "synchrotron radiation." Identify which emission properties relate to thermal and synchrotron (nonthermal) radiation. Drag the appropriate labels to their respective targets. -Thermal -Synchrotron 1. radiation peaks at a characteristic frequency. 2. radiation is consistently stronger at lower frequency (longer wavelength). 3. radiation depends on the temperature of the source. 4. radiation depends on the presence of magnetic fields.

1. radiation peaks at a characteristic frequency. -Thermal 2. radiation is consistently stronger at lower frequency (longer wavelength). -Synchrotron 3. radiation depends on the temperature of the source. -Thermal 4. radiation depends on the presence of magnetic fields. -Synchrotron

The graph shows that galaxies with high speeds as measured from Earth are __________. A) moving away from Earth and are farther from Earth than galaxies with lower speeds B) moving toward Earth and are farther from Earth than galaxies with lower speeds C) moving away from Earth and are closer to Earth than galaxies with lower speeds D) moving toward Earth and are closer to Earth than galaxies with lower speeds

A) moving away from Earth and are farther from Earth than galaxies with lower speeds

The age of the universe is related to the slope of the graph of Hubble's law, and current data put the age of the universe at about 14 billion years. Suppose that future observations showed that the slope of Hubble's law on the graph is actually steeper than that shown. In that case, the age of the universe would be _________ than 14 billion years because the universe is expanding ______ than current data suggest. (Each choice gives words to fill in the two blanks, separated by a slash.) A) younger / more rapidly B) younger / more slowly C) older / more rapidly D) older / more slowly

A) younger / more rapidly

Edwin Hubble photographed galaxies and classified them according to their apparent shapes. Label the diagram of Hubble's classification system according to the broad categories of galactic shapes. Drag the appropriate labels to their respective targets. -Elliptical -Spiral -Irregular -Barred-spiral

A: -Elliptical B: -Spiral C: -Barred-spiral D: -Irregular

The nucleus of an active galaxy contains several components, as shown in the figure below. Drag the appropriate labels to their respective targets. Note that not all labels will be used. -Jets of high-speed particles -Magnetic field lines -Accretion disk -Supermassive black hole -Densely clustered star

A: -Jets of high-speed particles B: -Magnetic field lines C: -Accretion disk D: -Supermassive black hole

Imagine that when we looked out into the universe we found that the light from all galaxies was blueshifted (rather than redshifted) and that the light from the most distant galaxies was blueshifted by the greatest amount. Which statement best describes what we would conclude about the motions of galaxies in this case? A) All are moving toward Earth, with nearby galaxies moving faster than distant galaxies. B) All are moving toward Earth, with distant galaxies moving faster than nearby galaxies. C) All are moving away from Earth, with nearby galaxies moving faster than distant galaxies. D) All are moving away from Earth, with distant galaxies moving faster than nearby galaxies.

B) All are moving toward Earth, with distant galaxies moving faster than nearby galaxies.

By looking at the graph, what can we say about the galaxies that have the lowest speeds? A) They are moving away from Earth and are farther from Earth than galaxies with high speeds. B) They are moving toward Earth and are farther from Earth than galaxies with high speeds. C) They are moving away from Earth and are closer to Earth than galaxies with high speeds. D) They are moving toward Earth and are closer to Earth than galaxies with high speeds.

C) They are moving away from Earth and are closer to Earth than galaxies with high speeds.

he irregular classification is in some ways a method of dealing with galaxies that are clearly not elliptical or spiral in shape. Select the properties associated with irregular galaxies. Check all that apply. A) They have tightly wound spiral arms. B) They all have centrally concentrated starlight. C) They exhibit vigorous star-forming activity. D) They are rare. E) Some show evidence for prior collision or close encounter with another galaxy. F) They are typically smaller than spiral galaxies.

C) They exhibit vigorous star-forming activity. E) Some show evidence for prior collision or close encounter with another galaxy. F) They are typically smaller than spiral galaxies.

The most successful model for explaining nuclear activity in galaxies involves a supermassive black hole that is gravitationally accreting matter from its surroundings. According to this model, different regions of the active galactic nucleus produce different types of radiation. Referring to the figure, match the region with the type of radiation being emitted. Drag the appropriate labels to their respective targets. -Infrared -None -X-ray -Radio

Dusty donut: -Infrared Supermassive black hole: -None Accretion disk: -X-ray Magnetized jet: -Radio

Astronomers observe galaxies and categorize them according to four different kinds of shapes: elliptical, spiral, barred-spiral, and irregular. In addition to shape, each of the four different galaxy types can be described by other common characteristics. Match the following characteristics with their corresponding galaxy type. Drag the appropriate items to their respective bins. -Round, no disk, very little gas and dust, only old stars. -Central bulge, flattened disk, spiral arms, gas, dust, young stars. -Elongated central structure, flattened disk, spiral arms, gas and dust, young stars. -Asymmetric, often with gas, dust, and young stars.

Elliptical galaxy (E): -Round, no disk, very little gas and dust, only old stars. Spiral galaxy (S): -Central bulge, flattened disk, spiral arms, gas, dust, young stars. Barred-spiral galaxy (SB): -Elongated central structure, flattened disk, spiral arms, gas and dust, young stars. Irregular galaxy (Irr): -Asymmetric, often with gas, dust, and young stars.

Since the time of Hubble, astronomers have learned that the blue color observed in some galaxies is the result of recent star formation. The blue regions can be seen in the following figure, where the color differences are schematically depicted. This interpretation has been confirmed by multiwavelength observations that have revealed the presence of star-forming gas clouds in galaxies hosting newly formed O-and B-type stars. Sort the galaxy types according to their level of star-forming activity. Drag the appropriate items to their respective bins. -Elliptical galaxies -Barred-spiral galaxies -Irregular galaxies -Spiral galaxies

Little star-forming activity: -Elliptical galaxies Significant star-forming activity: -Barred-spiral galaxies -Irregular galaxies -Spiral galaxies